NEW YORK - U.S. stocks posted their worst loss since February on Wednesday, the Dow Jones industrial average finishing the day down more than 800 points.

The losses were widespread as bond yields remained high after steep increases last week. Companies that have been the biggest winners on the market the last few years, including technology companies and retailers, suffered steep declines.

The Dow gave up nearly 828 points, or 3.15 percent, to 25,600. The Nasdaq composite, which has a high concentration of technology stocks, tumbled 316 points, or 4.1 percent, to 7,422.

The S&P 500 index sank 95 points, or 3.3 percent, to 2,786, its fifth straight drop. That hasn't happened since right before the 2016 presidential election. Every one of the 11 S&P 500 sectors finished down for the day.

After a long stretch of relative calm, the stock market has suffered sharp losses over the last week as bond yields surged.

Squeezed margins

Gina Martin Adams, the chief equity strategist for Bloomberg Intelligence, said investors are concerned about the big increase in yields, which makes it more expensive to borrow money. She said they also fear that company profit margins will be squeezed by rising costs, including the price of oil.

The biggest driver for the market over the last week has been interest rates, which began spurting higher following several encouraging reports on the economy. Higher rates can slow economic growth, erode corporate profits and make investors less willing to pay high prices for stocks.

The 10-year Treasury yield rose to 3.22 percent from 3.20 percent late Tuesday after earlier touching 3.24 percent. It was at just 3.05 percent early last week.

Technology and internet-based companies are known for their high profit margins, and many have reported explosive growth in recent years, with corresponding gains in their stock prices. Adams, of Bloomberg Intelligence, said investors have concerns about their future profitability, too.

That's helped make technology stocks more volatile in the last few months.

'As stocks go up, tech goes up more than the stock market. As stocks go down, tech goes down more than the stock market,'' she said.